Ah yes, physics, the love of every smart child growing up. It shows us how the universe works and how various things behave the way they do, while all of this comes under the general term of physics, there are two types of it. The first one being the general or motion physics deals with the basic properties of the objects and forces which we can observe and feel, this is usually taught in schools and even in high school. Then comes quantum physics, perhaps one of the most difficult subjects to study and it indeed is as difficult as rocket science if not more.
What is Quantum Physics?
While all of us have studied physics to some degree so how come quantum physics gets so much respect and is deemed so difficult for regular individuals. Because unlike our observable reality the laws of physics break when we go to a molecular level and see how particles seem to be obeying a completely new set of rules. This tiny world and study of it are known as quantum physics or mechanics. Though it may suggest that it is only used for theories, it does have many applications such from creating nanometer precise microscopes to space travels and understanding the nature of extreme bodies such as black holes.
Perhaps one of the most popular fundamental forces of the universe was discovered by Sir Isaac Newton and taught first thing in the schools. Physicists have been theorizing and using gravity to educate students on how this invisible force pulls, as the mass of an object exerts a force on surrounding objects with less mass, while they have gravitational force as well but it is minuscule and ultimately, object with higher mass pulls the smaller ones, that is how everything that is thrown up always falls on Earth. But when we go to a molecular level all of this understanding falls apart and particles behave as if they are unaffected by gravity. While gravity still exists at this level it is ridiculously weak, so weak that it would be like comparing a proton to the size of the observable universe, you get the point.
While it is hypothesized, the theories that support the idea of quantum gravity are the superstring theory and quantum loop gravity.
- Superstring Theory: In physics, particles are considered as one point but in this theory, the building blocks of matter are replaced with tiny strings that vibrate, and some physicists even theorize that these are what holds the universe together. According to scientists, the various vibrational patterns generates a different kind of particles and a particular vibration results in gravitons and ultimately gravity.
- Quantum Loop Theory: So now we head to Albert Einstein’s theory of general relativity which gives rise to many subcategories of quantum mechanics. In this Einstein stated that space is bent by the mass of objects and this generates lows and highs in the fabric of space which creates ripples in the space fabric. Unfortunately, his idea of gravity simply doesn’t work with quantum physics. Therefore, scientists do not take background space and time into consideration and deduced a set of time and size and state particles cannot go beyond that. As you can imagine this is a complex theory and scriptures of mathematical equations have been written for it.
- Graviton: While we have a quantum theory of three fundamental forces, so the idea of having the fourth ones only seems logical. As particles such as photons were first theorized and then found way later, physicists made up a particle known as graviton but more complications exist with this. If such particle exists it must exhibit the same properties as gravity; it should have an infinite range, it should have a neutral charge, and must have a spin of 2 to make it attract particles towards itself. But that’s the thing, graviton doesn’t exist and even with technology say from hundreds of years from now, scientists believe we might not be able to find it.
To conclude, quantum gravity is still a concept and possibilities exist that may prove that gravity is quantized, however, at this point, we are unable to find a piece of evidence that may prove it exists. In the future, we might be able to come to a better understanding of gravity in the quantum realm but that day is not today.